Have always wonder which currency would the world accept if only one currency was to be used. Maybe the dollar?, don't think so, The British won't tolerate that.
Cryptocurrency?. Maybe. Until the advent of cryptocurrency, I never thought that would be possible but it seems possible.
The world is not too far from a unified currency.
I'm very confused why, how out of the 195 countries in the world, you think that "The British" have some sort of special influence over what would be a universal currency? Do you know why countries like to have control of their own currencies in the first place? It is in part because if they are trusted and productive, they can expand/contract the money supply to suit their economic needs. Just look at China, it likes to heavily control the exchange rate of the Yuan because they can export goods cheaply, which allows them to undercut other countries manufacturing bases and drive out competition, which has been critical to their success over a few decades. The Euro crisis back around 2010 was exasperated for Greece because the ECB had control of their currency supply and would not allow them to devalue the currency in order to pay debts off. Governments around the world have little interest in losing control of their currencies although they might start allowing digitized versions because cash and coins (especially during Covid) have become more obselete. Besides that, the dollar is effectively a "reserve currency" which is the closest you'll probably find towards a single global monetary unit for many years to come.